Feasibility - gps speed to control electric power steering boost

Hi everyone,

I’m new to this forum and the world of Arduino so need a bit of advice.

I’m just about to fit electric power steering into a classic car. There’s not much room to work with and I’m having to use a micro motor and the only control system available is a variable resistor that is used too adjust boost anywhere from fully off to fully assisted.

This is an old vehicle and there’s nothing to take a speed signal off unless we fit some kind of sensor on a driveshaft or the speedo cable.

I’d say we need 2 to 4 steps between 0mph and about 40mph when boost would be turned off. There’s not a wild amount of room to play with especially for mechanics but do have some behind dashboard space for electronics.

Could A GPS speed sensor b Arduino be made to work to control the boost.

What set up are you using ? - is it an electric power steering set up from an another car, complete with ECU and you just want to change the amount of assistance with speed via an input? Hope so ; please don’t make your own system !!

I would not use gps - if you lost the signal and the car then had max assistance whilst you were going fast , it could get exciting .
Getting a speed signal with a sensor off a hub bolt of whatever is probably easier anyway.

Could A GPS speed sensor b Arduino be made to work to control the boost.

Not reliably.

I tried a GPS speedo on my car. It can take minutes for the unit to catch the satellite signals after powering and it can lose the signals because of external conditions or for no apparent reason. There was also significant latency, ie, a lag b/w true and displayed speed.

I changed to using a magnet fitted to a front wheel driveshaft and a Hall Effect sensor mounted on a frame member so that the magnet passes just a few mm from the sensor.

Fed the signal to a Nano and calculated the speed from the time for a single rotation. Always works, zero drift or random error. Accuracy depends on how you calibrate it.

Could A GPS speed sensor b Arduino be made to work to control the boost.

What would be the default when, inevitably, the GPS had no signal and thus no idea of the speed; is power assist on or power assist off ?

For an underground car park (no GPS signal) I presume you need power assist on, so what would happen when your travelling at speed through a road tunnel and the GPS also has no signal ?

Jpom is totally correct.
Simply for the fact GPS speed lags behind reality makes it unworkable

There are GPS-sensors with dead reckoning, that work quite well under these conditions. But you always us the built in buffe circuit on the gps module, so the boot delay is near zero.

What's the top speed of this car?

Sounds like you don't need a precise measurement of speed.

Maybe some other sensor would work. What indicates speed? Vibration? Sound level from a wheel? What about driver input?

Is this for use on public roads? If so, perhaps we shud all increase our public liability insurance.

Electric power steering requires major main steering shaft modifications for crown and sun gear operation.

Any mod to any street going machine anywhere would require (at bare minimum)quite expensive certification.